really old speaker

[Kiwick]

Hi,

I've found this old speaker in a junkyard, there's no brand on it, it's about 9" and has "patented made in USA" embossed on the frame, and a gold-black label with several patent numbers, the later ones are dating from 1926, maybe anyone knows this speaker's manufacturer and age? pics attached.

The spider is made from some sort of brown phenolic laminate, and the cone surround is made of thin black leather.

the leather surround had a couple of cracks which i glued together with a thin layer of diluted Elmers wood glue, but the leather, while mostly intact, seems to be really dry, is it a good idea to apply some leather conditioner oil to it or it's best left as is?

The VC reads 3.5 ohms and the FC reads 1100 ohms, what's the right voltage to energize the FC? it seems to work reasonably well with 35 volts but i think it could get more sensitive with higher voltages, i've hooked this speaker to the output of a 3-watt cassette player and it sounds nice.

Probably a super-rare find here in Italy!